Well done Bob,stick with it,when you do the roller exercises,don't do more than 3 cycles,and then rest that exercise for a day before doing it again,it really burns when you first do it,and it only works if you keep your arms fully extended and locked at the elbows,once it stops hurting put a centimetre of water in the carton and carry on,filling in small increments once you can comfortably deal with the last increase,it will really help your hold,and it's well worth it.
Good shooting!
Neale
Steyr LG110 Hunter,AA410 in Gary Cane stock,HC, Steyr LP50,Morini 164ei,Morini CM84e,Anschutz 1417 thumbhole,Rimfire Magic 10/22,Anschutz 1913,Rieder and Lenz Z2,Keppeler 6mmbr